Pump produced in a substrate

ABSTRACT

A pump having a first substrate extending in a plane, a cavity formed in a top face thereof and having fixed lateral walls that delimit sides thereof, intake and evacuation channels formed in the top face, each parallel to the plane from an inlet to an outlet, the outlet of the intake channel and the inlet of the evacuation channel opening into the cavity at the walls, a second substrate bonded onto the top face and forming a fluid-tight chamber, a membrane forming a wall of the chamber and being deformable between suction and positions to suck or discharge fluid, and non-return valves formed in the top face, each having a proximal side anchored to the first substrate. The proximal side of the first is between the orifices of the intake channel, and the proximal side of the second valve is between the orifices of the evacuation channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

Under 35 USC 119, this application claims the benefit of the priority date of French Patent Application 1257411, filed Jul. 31, 2012, the content of which is herein incorporated by reference.

FIELD OF DISCLOSURE

The invention relates to a pump produced in a substrate and to a method for manufacturing this pump.

BACKGROUND

In particular, the invention relates notably to micropumps, that is to say pumps which are microsystems.

Microsystems are, for example, MEMS (Micro-ElectroMechanical Systems). These microsystems differ from macroscopic mechanical systems also by their method of manufacture. These microsystems are produced by using the same collective manufacturing methods as those used to produce microelectronic chips. For example, the microsystems are produced from wafers made of monocrystalline silicon or of glass machined by photolithography and etching (for example, Deep Reactive Ion Etching, DRIE) and/or structured by epitaxial growth and metallic material deposition.

By virtue of these manufacturing methods, the microsystems are small and generally have machined pieces or parts of pieces of which at least one of the dimensions is of the micrometric order. The dimension of micrometric order is generally less than 200 μm and, for example, between 1 and 200 μm.

The known pumps comprise:

-   a first substrate extending essentially in a plane called “plane of     the substrate”, -   a cavity formed in a top face of the first substrate and delimited     on the sides by fixed lateral walls, -   channels, for the intake and evacuation of a fluid, formed in the     first substrate, each of these channels extending parallel to the     plane of the substrate from an inlet orifice to an orifice outlet,     the outlet orifice of the intake channel and the inlet orifice of     the evacuation channel opening directly into the cavity at the fixed     lateral walls, -   a membrane sealing the cavity to form a fluid-tight chamber, this     membrane being deformable:     -   from a suction position to a discharge position to discharge the         fluid outside the chamber via the evacuation channel, and     -   from the discharge position to the suction position to suck the         fluid into the chamber via the intake channel, -   a first and a second non-return valves, each non-return valve     comprising a proximal side anchored with no degree of freedom to the     first substrate.

The expression “substrate extending essentially in a plane” is used equally to designate flat substrates and substrates having slight flatness defects such as a slightly curved substrate or an uneven surface.

For example, such a pump is described in the following A1: WO 2011 133 014 A1.

This known pump offers the advantage of being simple to manufacture because the intake and evacuation channels, the cavity and the valves are situated in one and the same plane and can therefore be simply produced by etching a same top face of the first substrate. Thus, through the arrangement of these elements, the number of substrates to be stacked one on top of the other to manufacture the pump of A1 is limited. In particular, the number of substrates to be stacked is less than that required to produce other pumps such as the pump described in the application WO 2007 128 705 A1.

Although the pump of A1 operates correctly, this configuration is likely to result in damage to the membrane and/or the valves, even malfunctioning of the non-return valves.

From the state of the art, the following are also known:

-   U.S. Pat. No. 5,816,780 A, -   EP 0 398 583 A2, -   Wijngraad Van Der W et A1: “The first self-priming and     bi-directional valve-less diffuser micropump for both liquid and     gas”, Proceedings of IEEE 13th annual international conference on     micro-electro-mechanical systems, MEMS 2000, Miyazaki, Japan, Jan.     23-27, 2000, pages 674-679.

SUMMARY OF THE INVENTION

The invention therefore aims to improve the pump of Al to remedy these malfunctions while retaining its manufacturing simplicity.

It has been discovered that at least a part of the malfunctions of the pump of A1 originated from the fact that, from time to time, when the membrane is displaced to its discharge position, it comes into contact with the valves. This contact can block the valve and prevent its displacement to its closed position or damage the valve or the membrane.

In the above pump, the valves are situated inside intake and evacuation channels. They can therefore no longer be blocked or damaged by the displacement of the membrane. The operation of the pump is therefore improved.

Furthermore, the lateral face of the valves no longer needs to be much greater than the transversal section of the inlet and outlet orifices to be blocked. This simplifies their manufacture and also reduces the head losses as well as the volume of the dead spaces inside the chamber.

Moreover, the valves according to the invention are actuated by the pressure difference between the upstream and downstream sides of each valve which can therefore operate even without a mechanical actuator. However, the invention can use such mechanical actuators notably to allow for a dynamic control of the valves.

These embodiments also offer the following advantages:

-   the presence of a shoulder on which the free periphery of the valve     rests in its closed position makes it possible to limit the leaks in     the direction that is the reverse of the planned fluid flow     direction; -   using a flexible valve makes it possible to obtain a non-return     valve that is only actuated by the pressure difference in the fluid     between the upstream and downstream sides of the valve; -   having the outlet orifice of the intake channel facing the inlet     orifice of the evacuation channel makes it possible to decrease the     head losses; -   producing the membrane in a second substrate bonded onto the first     substrate makes it possible to simplify the manufacturing of this     pump; -   the fact of having the proximal side of the valve parallel to the     plane of the first substrate simplifies the manufacturing of the     valve.

The embodiments of this method may comprise one or more of the features of the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood on reading the following description, given solely as a nonlimiting example and made with reference to the drawings in which:

FIG. 1 is a schematic illustration of a pump in vertical cross-section;

FIG. 2 is a schematic illustration in plan view of a first substrate of the pump of FIG. 1;

FIG. 3 is a flow diagram of a method for manufacturing the pump of FIG. 1;

FIGS. 4 to 10, 12 to 16 and 18 are schematic illustrations, in vertical cross-section, of different steps in manufacturing the pump of FIG. 1;

FIGS. 11 and 17 are schematic illustrations, in plan view, of the substrates manufactured during the implementation of the method of FIG. 3.

DETAILED DESCRIPTION

In these figures, the same references are used to designate the same elements.

Hereinafter in this description, the features and functions that are well known to a person skilled in the art are not described in detail.

FIG. 1 represents a pump 2 of planar type that is to say with the main pump elements situated in one and the same plane parallel to a face of one and the same substrate. This pump 2 is designed to allow a very precise volume of a fluid to be pumped. The fluid can be a liquid such as water or a solution to be injected. The fluid may also be a gas. The 20 direction of flow of the fluid inside the pump is indicated by an arrow F. Hereinafter in the description, upstream and downstream are defined relative to the direction of flow F.

The pump 2 is here a microsystem and can therefore be called micropump. Typically, the greatest width of the pump is less than 2 or 1 cm. This greatest width is generally greater than 1 mm.

The pump 2 is produced from only two substrates 4 and 6 bonded one on top of the other. The bonding interface 8 between these two substrates 4 and 6 is shown by an axis in FIG. 1. This bonding interface 8 extends in a horizontal plane parallel to mutually orthogonal directions X and Y. A direction Z orthogonal to the directions X and Y represents the vertical direction. Hereinbelow, the terms “top”, “bottom”, “above” and “below” are defined in relation to this direction Z.

The substrate 6 is above the substrate 4. The substrate 4 comprises:

-   a horizontal top face 10 (FIG. 2) turned towards a horizontal bottom     face 12 of the substrate 6, and -   a horizontal bottom face 14 on the side opposite to the face 10.

The substrate 6 also comprises a horizontal top face 16 on the side opposite to its bottom face 12.

The different layers forming each of these substrates will be described in more detail with reference to the method of FIG. 3. FIG. 2 represents a plan view of the pump 2 when the substrate 6 is omitted.

Hereinbelow, the description of the pump 2 is given with reference to these two FIGS. 1 and 2.

The pump 2 has a vertical cutting plane 18. Here, this plane 18 is parallel to the directions Y and Z. Hereinbelow, only the elements of the pump 2 in the left-hand part of this plane 18 are described in detail.

The substrate 4 comprises, in succession in the direction F of flow of the fluid:

-   a vertical hole 20 passing right through the substrate 4, -   a rectilinear fluid intake channel 22, -   a fluid-tight chamber 24, -   a rectilinear fluid evacuation channel 26, and -   another vertical hole 28 passing right through the substrate 4.

One end of the hole 20 opens out in the bottom face 14. Here, this end is flared to receive, for example, a sleeve with which to connect the pump 2 to the outlet of a fluidic circuit.

The opposite end of the hole 20 opens out in the top face 10. This end is blocked by the bottom face 12 of the substrate 6.

The hole 28 is the symmetrical counterpart of the hole 20 relative to the plane 18.

The channel 22 extends horizontally parallel to the direction X. It extends from an inlet orifice 30 to an outlet orifice 32. The orifice 30 opens out in a vertical wall of the hole 20. The orifice 32 opens out in a vertical wall 34 of the chamber 24.

The transversal section of the channel 22 is, for example, rectangular. The top wall of the channel 22 is here formed by the bottom face 12 of the substrate 6.

The channel 26 is the symmetrical counterpart of the channel 22 relative to the plane 18. It extends from an inlet orifice 36 to an outlet orifice 38. The orifices 36 and 38 open out, respectively, in a vertical wall 40 of the chamber 24 and in the hole 28. The wall 40 is the symmetrical counterpart of the wall 34 relative to the plane 18.

The chamber 24 extends on either side of the plane 18. Here, this chamber 24 is a parallelepipedal which extends mainly horizontally. The chamber 24 defines a hollow space formed by the combination:

-   of a cavity hollowed out in the top face 10 of the substrate 4, and -   of a movable membrane 44 produced in the substrate 6.

The cavity is delimited in the substrate 4 by vertical walls, including notably the walls 34 and 40, and by a horizontal wall 42, also called bottom of the cavity.

The vertical walls and the bottom of the cavity form only a single block of material with the substrate 4 and are fixed.

The opening of this cavity opens out in the top face 10.

Here, the interior of the chamber 24 is empty, that is to say notably without any non-return valve.

The membrane 44 covers all of the opening of the cavity to form the fluid-tight chamber 24. The chamber 24 is tight to the pumped fluid.

The membrane 44 is deformed elastically between a suction position and a discharge position. When it is displaced from the discharge position to its suction position, it sucks the fluid into the chamber 24 via the channel 22. When it is displaced from its suction position to its discharge position, it discharges the fluid from inside the chamber 24 to the outside via the channel 26.

In FIG. 1, the membrane 44 is represented in a rest position. In this rest position, it extends horizontally.

In this embodiment, in the suction position, the membrane 44 is dished into the substrate 6. In this position, the top of the membrane 44 is retracted into the substrate 6 relative to its placement in the rest position of the membrane.

In the discharge position, the membrane 44 is dished into the cavity formed in the substrate 4. The top of the membrane 44 is then situated inside the cavity of the substrate 4. This displacement of the membrane on either side of its rest position makes it possible to maximize the pumped volume and therefore increase the volumetric displacement of the pump.

Here, the membrane 44 forms only a single block of material with the substrate 6. Its periphery is therefore fixed with no degree of freedom to the rest of the substrate 6.

The pump 2 also comprises an actuator 46 capable of converting the energy that it receives into a displacement of the membrane 44 between its suction and discharge positions. For example, the actuator 46 is a conventional actuator such as an electrostatic actuator or a piezoelectric actuator or a bimetallic actuator, such as a bimetallic strip, or a shape memory actuator or a thermo-pneumatic actuator.

In some cases, the actuator is partly or wholly combined with the membrane 44. Such is the case, when the membrane 44 is produced in a piezoelectric material or by a two-layer complex in which each layer has a coefficient of expansion different from the other to form a bimetallic strip. The energy received by the actuator may be electrical energy or heat energy. Heat energy is for example used when the actuator comprises the bimetallic complex. Obviously, the actuator according to the invention can also be a device external to the membrane and linked thereby by a mechanical attachment element.

The channel 22 comprises a non-return valve 50 capable of preventing or limiting the circulation of the fluid in the direction opposite to the direction F. This valve 50 is situated upstream of the orifice 32 and downstream of the orifice 30 inside the channel 22. It can be displaced between an open position and a closed position. In the open position, it allows the fluid to flow in the direction F more easily than in its closed position. In its closed position, it prevents the flow of the fluid in the reverse direction of the direction F. Here, in its closed position, the valve 50 extends parallel to the plane 18. In its open position, represented in FIGS. 1 and 2, the valve 50 is inclined in the downstream direction.

The valve 50 is a flexible blade of the same transversal section as the transversal section of the channel 22 but of slightly smaller dimension. Here, the valve 50 therefore has a rectangular transversal section. The height of this valve h_(c) in the direction Z and its width L_(c) in the direction Y are, for example, at least 0.1 μm or 1 μm less, respectively, than the height and the width of the channel 22 in the same directions.

The valve 50 is displaced between its open and closed positions by rotation about an axis securely attached to the substrate 4. To this end, a proximal side of the valve 50 is anchored with no degree of freedom to one of the walls of the channel 22. Here, this proximal side is anchored onto a vertical wall of the channel 22. Thus, the valve 50 forms only a single block of material with the substrate 4.

The valve 50 is flexible to be deformed elastically between its open and closed positions only under the action of the fluid which is flowing. To this end, the thickness e_(c) of the valve 50 is at least five or ten times less than its width L_(c) or than its height h_(c). Typically, the width L_(c) and the height h_(c) are greater than 50 or 100 μm. Consequently, typically, the thickness of the valve 50 is less than 10 μm or 5 μm.

In its rest position, that is to say in the absence of pressure difference between the upstream and downstream sides of the valve 50, the latter is in a rest position situated, for example, between its open position and its closed position.

In the closed position, the free periphery of the valve 50 is separated from the walls of the channel 22 and from the bottom face 12 of the substrate 6 by a gap. For example, this gap is greater than or equal to 0.1 or 1 μm. The free periphery of the valve 50 corresponds to the periphery of the valve 50 minus its anchored side.

More specifically, here, the free periphery of the valve 50 is formed:

-   on a horizontal top side facing the bottom face 12, -   on a horizontal bottom side facing the bottom of the channel 22, and -   on a vertical distal side situated on the side opposite and parallel     to the proximal side of the valve 50.

In this embodiment, to eliminate almost all of the leaks at least during operation via this gap, the channel 22 comprises a shoulder 54 on which the free periphery of the valve 50 directly bears mechanically when the latter is in its closed position. This shoulder blocks virtually all of the gap when the valve 50 is in its closed position. The shoulder 54 is situated upstream of the valve 50.

For example, the shoulder 54 is formed by two abutments 56 and 58. The abutments 56 and 58 are fixed, with no degree of freedom, respectively, to the substrates 4 and 6.

The abutment 56 here is “L” shaped. The horizontal bar of the “L” extends parallel to the direction Y over the entire length of the bottom of the channel 22. The vertical bar of the “L” extends parallel to the direction Z along the vertical wall of the channel 22 facing the wall of the channel 22 onto which the proximal side of the valve 50 is anchored. Here, the vertical bar of the “L” extends over at least 80% of the height of the channel 22.

In the closed position, the bottom and distal sides of the valve 50 rest mechanically on, respectively, the horizontal and vertical bars of the “L” of the abutment 56.

The abutment 58 extends parallel to the direction Y along the bottom face 12. This abutment 58 is facing the horizontal bar of the “L” of the abutment 56. Its length is greater than 70 or 80% of the width of the channel 22 in the direction Y. In the closed position, the top side of the valve 50 rests on the abutment 58.

The channel 26 comprises a non-return valve 60. This non-return valve 60 is associated with the valve 50 on the other side of the plane 18. In FIGS. 1 and 2, it is represented in its closed position. This valve 60 is produced in the same way as the valve 50.

In its closed position, the free periphery of the valve 60 bears directly on a shoulder 62 of the channel 26 situated immediately upstream of this valve 60. The shoulder 62 is, for example, identical to the shoulder 54.

The operation of the pump 2 is as follows. Initially, the valves 50 and 60 are in their rest position between the open and closed positions. The membrane 44 is then displaced from its rest position to its suction position. This creates a depression inside the chamber 24. The pressure difference which then exists between the upstream and downstream sides of the valve 50 provokes the displacement of this valve 50 from its rest position to its open position. The fluid can then enter into the chamber 24 via the channel 22. Conversely, the valve 60 changes from its rest position to its closed position because of the shoulder 62. Thus, it prevents the fluid from entering into the chamber 24 via the channel 26.

When the chamber 24 is filled, the pressure upstream and downstream of the value 50 is balanced. The valve 50 changes from its open position to its rest position by elastic deformation.

Then, the membrane 44 is displaced from its suction position to its discharge position. This creates an overpressure inside the chamber 24. The valve 50 changes from its rest position to its closed position in which it is in abutment against the shoulder 54. Conversely, the pressure difference between the upstream and downstream sides of the valve 60 provokes the displacement of this valve 60 from its rest position to its open position. In the open position, it allows the fluid to escape from inside the chamber 24 to the hole 28.

When the chamber 24 is emptied, at least partly, the pressure between the upstream and downstream sides of the valve 60 is balanced. The valve 60 then returns, by elastic deformation, from its open position to its rest position. A new cycle of pumping a new volume of the fluid can then commence.

A method for manufacturing the pump 2 will now be described with reference to the method of FIG. 3 and using the various views of these FIGS. 4 to 18. To simplify these FIGS. 4 to 18, in each of these figures, only the part to the left of the plane 18 has been represented. Furthermore, the manufacturing method will now be described in the particular case where the depth of the chamber 24 is equal to the depth of the channels 22 and 26.

The method of FIG. 3 comprises two phases 80 and 82 which can be run mostly in parallel.

The phase 80 is a phase of manufacturing of the substrate 4 whereas the phase 82 is a phase of manufacturing of the substrate 6.

At the start of the phase 80, during a step 86, the substrate 4 is supplied. Here, it is a BSOI (Bonded Silicon On Insulator) substrate. The substrate 4 comprises a layer 88 (FIG. 4) of silicon on an electrically insulating layer 90, which is in turn arranged directly on a support 92. The layer 88 has a thickness of between 10 and 200 μm. The layer 90 has a thickness of between 0.5 and 2 μm. The support 92, which is intended to rigidify the substrate, to this end has a thickness greater than 500 μm or 725 μm.

Then, during a step 94, a layer of oxide is deposited on the top face. For example, this deposition is produced by a plasma-enhanced chemical vapour phase deposition, better known by the acronym PECVD. Then, a lithography step is carried out followed by etching of this layer of oxide to form a mask 96 (FIG. 5). The etching is, for example, carried out by reactive-ion etching, better known by the acronym RIE.

During a step 98, a layer of oxide is deposited on the bottom face of the substrate 4. For example, this deposition is carried out according to the PECVD method. Then, a lithography step is carried out followed by an etching of this layer to form a mask 100 which delimits the placement of the hole 20 (FIG. 6). Still during this step 98, the bottom face of the substrate is then etched to form a first part of the hole 20. This etching is, for example, carried out according to a deep reactive-ion etching method, better known by the acronym DRIE.

During a step 102, a lithography step is carried out to deposit a mask 104 of resin (FIG. 7). This mask 104 defines the placement of the valve 50, of the channel 22, of the chamber 24 and of the abutment 56.

During a step 106, the top face is etched through the mask 104 (FIG. 8). For example, this etching is carried out according to the DRIE method by using the layer 90 as a stop layer. This etching makes it possible to form the channel 22, the top end of the hole 20, 25 the valve 50 and the cavity of the chamber 24.

During a step 108, the mask 104 is removed (FIG. 9).

Then, an etching is carried out from the top face by using the mask 96. This etching is, for example, carried out according to the DRIE method. This etching makes it possible to form the abutment 56.

During a step 110, the valve 50 is released by implementing a wet phase or vapour phase HF etching (FIG. 10). This etching makes it possible also to remove the layer 100 and unblock the hole 20.

FIG. 11 is a plan view representation of the left-hand part of the substrate 4 thus manufactured.

In parallel, at the start of the phase 82, during a step 116, the substrate 6 is supplied (FIG. 12). This substrate is also a BSOI substrate for example. It comprises a layer 118 of silicon superposed on an electrically insulating layer 120, which is in turn superposed on a support 122. The thicknesses of the layers 118, 120 and of the support 122 are, for example, within the same bands as those given for the substrate 4 supplied during the step 86.

During the step 124, a layer of oxide is deposited on the layer 118 of silicon. Then, a lithoetching step is carried out followed by etching to form the abutment 58 (FIG. 13). During this step 124, the etching method implemented is, for example, the RIE method.

During a step 128, a mask 130 (FIG. 14) is deposited on the bottom face of the support 122. To obtain this mask, a layer of oxide is, for example, deposited according to the PECVD method and then lithography and etching steps are carried out to form the mask 130. The etching implemented is, for example, an RIE etching.

During a step 132, a metallic layer 134 (FIG. 15) is deposited on the layer 118. For example, it is deposited by the method known by the acronym PVD (Physical Vapour Deposition). The metallic layer then undergoes a lithography step followed by a step of etching of this metallic layer to form the metallic layer 134 forming most of the bottom face 12 of the substrate 6.

Finally, during a step 136, the membrane 44 is formed by etching the bottom face of the substrate 6 through the mask 130 (FIG. 16). During this etching, the layer 120 is used as a stop layer.

FIG. 17 represents the bottom face of the substrate 6 obtained on completion of the phase 82.

Then, once the substrates 4 and 6 have been manufactured, during a step 140, the top face 10 of the substrate 4 is bonded onto the bottom face 12 of the substrate 6 (FIG. 18). The pump 2 is then obtained.

Numerous other embodiments are possible. For example, different types of substrate can be used such as substrates of silicon, of polysilicon, SOI (Silicon On Insulator) substrates, glass, plastic, substrates of metal or of polymer.

In another embodiment, the channels and the cavity are not hollowed out but formed by deposition of successively structured layers one on top of the other.

As a variant, the suction position of the membrane 42 or, alternatively, its discharge position may be combined with the rest position.

In another embodiment, the pump 2 comprises a plurality of deformable membranes. For example, each of these deformable membranes is associated with a respective cavity.

The cavity may have the same transversal section as the channels 22 and 26. In this case, the cavity is distinguished from the channels only by the fact that it is covered by the movable membrane, this is not the case with the channels.

The suction and discharge channels can be on the same side of the chamber 24 and open into the chamber 24 in one and the same vertical wall.

There is no need for the intake and discharge channels to have the same transversal section. For example, the evacuation channel may be deeper and less wide than the intake channel.

The outlet orifice of the intake channel and/or the inlet orifice of the evacuation channel may occupy the entire surface of the lateral wall of the cavity in which they open out. In this case, this lateral wall no longer exists.

The pump 2 may also comprise a plurality of intake channels and a plurality of evacuation channels fluidically connected to the same chamber 24. In this case, each of these intake and evacuation channels comprises its own non-return valve.

The shoulder on which the non-return valve rests can be obtained by reducing the diameter of the channel upstream of the valve. In these conditions, the transversal section of the channel over its entire length upstream of the valve is smaller than the transversal section of this same channel over its entire length downstream of this same valve.

As a variant, the proximal side of the valve is anchored onto the bottom of the channel and not onto one of the vertical walls of this channel.

In another embodiment, the displacement of each valve is actuated by an electrical or heat actuator. For example, the actuator is based on a principle similar to those implemented to displace the membrane 44.

In a simplified embodiment, the shoulders are omitted. In practice, if the gap between the free periphery of the valve and the walls of the channel is sufficiently small, this results in negligible liquid leaks even in the absence of the shoulders.

The deformable membrane does not necessarily cover the opening of the cavity which opens out in the top face 10. For example, in another embodiment, the membrane is incorporated in one of the vertical walls or in the bottom of the cavity. In the latter case, the membrane may be produced in the substrate 4 as described in the article by Wijngaart Van Der W et A1 introduced in the introduction to this patent application. It is also possible to produce both a membrane in the first substrate and another membrane in the second substrate. 

1. An apparatus comprising a pump, said pump comprising a first substrate extending in a substrate plane, a cavity formed in a top face of said first substrate, said cavity having fixed lateral walls that delimit sides thereof, intake and evacuation channels for intake and evacuation of fluid, said intake and evacuation channels being formed in said top face of said first substrate, each of said intake and evacuation channels extending parallel to said substrate plane from an inlet orifice to an outlet orifice, said outlet orifice of said intake channel and said inlet orifice of said evacuation channel opening directly into said cavity at said fixed lateral walls, a second substrate bonded onto said top face of said first substrate and sealing said cavity to form a fluid-tight chamber, a membrane forming a wall of said fluid-tight chamber, said membrane being deformable from a suction position to a discharge position to discharge fluid outside said chamber via said evacuation channel, and from said discharge position to said suction position to suck fluid into said chamber via said intake channel, and first and a second non-return valves formed in said top face of said first substrate, each non-return valve comprising a proximal side anchored with no degree of freedom to said first substrate, wherein said proximal side of said first non-return valve is situated between said inlet and outlet orifices of said intake channel, and said proximal side of said second non-return valve is situated between said inlet and outlet orifices of said evacuation channel.
 2. The apparatus of claim 1, wherein each valve comprises a free periphery configured for displacement relative to said first substrate between an open position, in which said valve allows free passage to fluid circulating in a direction running from said intake into said evacuation channel, and a closed position, in which said valve blocks said passage of said fluid in said reverse direction, and wherein each channel comprises, between inlet and outlet orifices thereof, a shoulder on which most of said free periphery of said valve rests in said closed position and from which said free periphery of said valve is separated in said open position.
 3. The apparatus of claim 2, wherein said membrane is a thinned part of said second substrate bonded onto said top face of said first substrate, said second substrate further comprising an abutment protruding on a bottom face thereof, said abutment forming at least one part of said shoulder.
 4. The apparatus of claim 1, wherein at least one of said valves has a thickness that is at least five times smaller than a width thereof so as to allow displacement of said at least one of said valves between said open and closed positions by elastic deformation only under action of a pressure difference between downstream and upstream sides of said at least one of said valves.
 5. The apparatus of claim 1, wherein said outlet orifice of said intake channel is situated on a first side of said cavity and said inlet orifice of said evacuation channel is situated on a second side of said cavity, and wherein said intake channel and said inlet orifice face each other across said cavity.
 6. The apparatus of claim 1, wherein said proximal side of at least one of said valves extends parallel to said substrate plane.
 7. The apparatus of claim 1, wherein said proximal side of at least one of said valves extends at right angles to said substrate plane.
 8. The apparatus of claim 1, wherein said pump further comprises an actuator configured for converting received energy into a displacement of said membrane between its suction and discharge positions.
 9. The apparatus of claim 8, wherein said actuator is incorporated in said membrane and comprises at least one layer that is deformable in response to said received energy, said at least one layer forming part of said membrane.
 10. The apparatus of claim 8, wherein said actuator is separate from said membrane and mechanically connected to said membrane by a mechanical attachment element configured for transmitting a deformation of said actuator to said membrane.
 11. The apparatus of claim 1, wherein said pump comprises a plurality of combinations of said cavity, channels, membrane, and non-return valves.
 12. The apparatus of claim 1, wherein said membrane covers all of said cavity.
 13. A method for manufacturing a pump, said method comprising supplying a first substrate extending essentially in a substrate plane, said first substrate having a top face, forming, in said first substrate, from a top face thereof, a cavity delimited by fixed lateral walls, intake and evacuation channels, said channels extending parallel to said substrate plane from respective inlet orifices to respective outlet orifices, said outlet orifice of said intake channel and said inlet orifice of said evacuation channel opening directly into said cavity at said fixed lateral walls, and first and second non-return valves, each non-return valve comprising a proximal side anchored with no degree of freedom to said first substrate, bonding a second substrate onto said top face of said first substrate so as to seal said cavity to form a fluid-tight chamber, forming in one of said first substrate and said second substrate, a membrane forming a wall of said fluid-tight chamber, said membrane being deformable from a suction position to a discharge position to discharge fluid outside said chamber via said evacuation channel, and from said discharge position to said suction position to suck fluid into said chamber via said intake channel, wherein during said formation of said first and second non-return valves said proximal side of said first valve is situated between said inlet and outlet orifices of said intake channel, and said proximal side of said second valve is situated between said inlet and outlet orifices of said evacuation channel.
 14. The method of claim 13, said method further comprising forming, in each of said channels, between inlet and outlet orifices thereof, a shoulder on which most of a free periphery of said non-return valve rests in a closed position and from which said free periphery of said non-return valve is separated in an open position, said shoulder being formed partly on said first substrate and partly on said second substrate, before said bonding of said first and second substrates.
 15. The method of claim 13, further comprising forming said membrane in said second substrate, said membrane being configured to seal said cavity to form said fluid-tight chamber. 